Dear (insert brilliant undiscovered, undervalued author’s name here- which is mine in this instance),
Thank you for your recent email and your interest in (name of undeserving agency here). We are always eager to hear from writers who are serious about the business of writing. (And since this is a rejection, we obviously do not feel you are serious about the business of writing). Unfortunately I do not feel that I'm the right representative for your work. (And there it is. You know, you could have saved me some time agent and just sent me this last line in the email. Done and done. But no, let’s let the knife linger a little.)
I have to be very selective of what I choose to represent and all of my decisions are based on a frank assessment of the current needs of the literary markets. The fact that this work doesn't fit my narrow criteria for representation does not mean it couldn't find a home elsewhere. (Ah, the old, “it’s not you, it’s me” line. Love it. This reads like a break-up, doesn’t it?) I urge you to submit your work to other agencies that may be more suited to this type of material. (There are plenty of other fish in the sea, just please stop fishing at my agency).
Well, there it is. The worst thing that can happen when you are querying agents. In all actuality, it’s not that bad. It’s just what you decide to do after you get a few of these in your inbox that will separate you from the thousands of other authors out there with unpublished work. Ugh, thousands...heaven help us all...